This is only for Fairview Templates currently. If you have the Fairview Template on your website you won't have the Share to LinkedIn button yet.
As Google+ makes it exit, Brixwork Update Version 4.477~4.479 has added a brand new LinkedIn button on every Brixwork website, as you may find it at the bottom of the page.
If you don't want the LinkedIn button, you can disable it following these steps:
Go to your backend
Once you Logged In, go to the "Settings" Tab
Go to the "Social Settings" Tab, and scroll until you find the LinkedIn section
Erase the URL in this section, then scroll and click "Save & Next"